The hypothesis of the "Losartan Intervention for Endpoint Reduction in Hypertension (LIFE)" trial is that, compared to atenolol, losartan will reduce the incidence of cardiovascular morbidity and mortality by 15% in patients with essential hypertension and left ventricular hypertrophy (LVH). The primary endpoint is the combined incidence of cardiovascular morbidity and mortality. The primary objective is to evaluate the long- term effects (=/> 4 years) of losartan compared to atenolol in hypertensive patients with documented LVH on the combination of cardiovascular mortality and morbidity (cardiovascular mortality defined as death due to fatal myocardial infarction [MI], fatal stroke, sudden death, progressive heart failure, other cardiovascular deaths; cardiovascular morbidity defined as nonfatal MI [excluding silent MI] and nonfatal stroke). The LIFE Study includes the following substudies: QUALITY OF LIFE (Substudy ID No. 133-03)--The purpose of this substudy is to assess differences in quality of life among patient with hypertension and LVH who are treated with losartan versus atenolol at 1, 2, 6, and 12 months of therapy. This substudy will examine the treatment-related influences, as defined by patient responses on the health-related domain (psychological well-being) score for vitality (a subdomain under psychological well-being) and the symptom inventory item relating to tiredness/fatigue. These responses are recorded on a self-administered quality of life (QoL) questionnaire, which has been specifically designed for hypertensive clinical studies. This questionnaire is a battery of scales utilizing groups of existing, validated QoL instruments. AFRICAN AMERICAN ECHO-SUBSTUDY FOR LIFE TRIAL (Substudy ID No. 133-05)-- The LIFE trial proposes to conduct an echocardiographic substudy in 12% of the study population in each country. Approximately 360 African American subjects will be followed in the U.S. (goal for total U.S. patients is 3,000). The presence of LVH by ECG (Cornell criteria) is a major inclusion criterion for the main LIFE trial and the comparison of LVH regression by ECG is listed as a study objective; however, several studies have documented that the assessment of LVH by ECG in Blacks is significantly less accurate than in other populations. The diagnosis of LVH by echocardiogram was similar in both populations. The LIFE trial will use a supposedly more accurate modification of the Cornell criteria (QRS voltage duration product) for LVH assessment; however, this method has not been adequately evaluated in significant numbers of Black hypertensives.